While the field of HVAC ducting is relatively mature, cost pressure drives a constant need to develop new and improved ducting, parts, manufacturing methods, and techniques for assembling ducting. Due to the high cost of labor, improved ducting that can be more efficiently assembled, for example, by reducing the number of laborers required to piece together an assembly, provides a significant cost advantage. Relatedly, new designs for ducting and/or parts can aid in improved assembly efficiency. Additionally, manufacturing techniques for ducting and/or parts can be improved to produce finished products as inexpensively as possible.
With regard to inefficiencies in assembling ducting, a typical process for assembling two lengths of HVAC ducting requires two laborers: one to push on the end of one of the two duct sections to engage the two sections together, and a second to secure the connection between the two sections, such as by screws, connection bands, or rivets. Ducting parts that improve the assembly process efficiency, for example, by allowing assembly to be accomplished by a single laborer, would provide a cost-saving benefit.
With regard to manufacture of ducting and connectors, spin-forming, roll-forming, stamping, and bending metal strips into a finished product are known to those of skill in the art. However, despite the maturity of HVAC manufacturing processes, new techniques, and new ways to apply known techniques, can improve manufacturing efficiency and can also enable the formation of new connector shapes previously not possible.
One area of difficulty in manufacturing HVAC ducting and connectors is the limitation created by roll forming, one of the most popular manufacturing techniques. Specifically, roll forming is limited generally to sheet-metal thinner than 10 gauge because roll forming causes tearing or breaking of sheet metal in the production of connectors (e.g., flanged rings) from thinner sheet metal.
The predominate means of manufacturing HVAC ducting is in the form of spiral seam tubes made up of helical wound sheet-metal strips with the strips interconnected by means of lock seams. The lock seams stand out from the outer duct surface. Because the lock seams create a structurally weak point in the duct, spiral ducting is difficult to further shape, using a technique such a spin forming. However, techniques that would allow for further shaping spiral ducting would be desirable to provide a new means for improving manufacturing efficiency of ducting and connectors for HVAC systems.